Altrhein Maxau, Protected natural area in Karlsruhe, Germany.

Altrhein Maxau is a protected nature reserve near Karlsruhe consisting of old Rhine branches and meanders that wind through the landscape like tangled ribbons. The site also includes Knielinger Lake and connected wetland habitats that provide homes for numerous plants and animals.

The old Rhine arm at Maxau is a remnant meander left when the Rhine shifted its bed naturally, not through any nineteenth-century straightening. The area was designated a nature reserve in 1980, nine years before the adjacent Burgau reserve, and later became part of the Natura 2000 network as both an EU bird protection area and an FFH site. It was created within the LIFE project "Lebendige Rheinauen bei Karlsruhe".

The reserve serves as a refuge for bird watchers and nature lovers who come to observe dozens of bird species in their natural habitat. Visitors walk the quiet paths to experience the landscape and learn about local ecological systems.

Access is by well-marked paths that loop around the lake and wetland areas, suitable for walkers of all abilities. Information boards at various spots help visitors understand the plants and wildlife they encounter.

The reserve also serves as a regeneration zone for the directly connected Knielinger See gravel lake, a function named in its protection purpose alongside the preservation of the old Rhine meanders. The site lies within the EU bird protection area of the Rhine lowland between Elchesheim and Karlsruhe and the FFH area between Wintersdorf and Karlsruhe, and was established under the LIFE project "Lebendige Rheinauen bei Karlsruhe".